Welcome to the madhouse...! Most shooters use diving bottles, a 7litre 300bar is a good choice, and with a hose, gauge, etc. costs about £150-170.
The air must be dry, as any moisture can cause damaging rust in the gun.
A pump with a DriPak filter is not much cheaper than a bottle, and hard work.
I don't know anything about commercial air... would it fit in the boot of your car? You might run into security problems getting a gun in and out of your place of work. It's a good idea to join a club, and see what other people are doing.
Cheers,
Gus
PS don't use anything but air.. see the "sticky" entitled "Just say NO!"
The ox is slow, but the earth is patient.